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In general you get a lot of points for being where the action is. As you said, you can get a lot of points bottom lane by taking the opposing point - but you also get a lot of points for re-capturing your point.
When you think about it, the total number of caps for both teams has to be pretty even; it can't get any more lopsided than +/-3 for either team, simply because things flip back and forth. So it's really just a question of how those points from capping are distributed amongst your team.
Same thing with kills - making 1:1 kill/death trades can be really good for you, or it could be really bad, but it always moves your score up.
I do agree with FDru that the extra gold for having multiple people cap a point seems like a really bad incentive, since that would almost always be a bad play - except for the fact that it gives extra gold.